"Because a lot of people who go into prison go into prison straight -- and when they come out, they're gay," Carson said. "So, did something happen while they were in there? Ask yourself that question."

"Although much research has examined the possible genetic, hormonal, developmental, social and cultural influences on sexual orientation, no findings have emerged that permit scientists to conclude that sexual orientation is determined by any particular factor or factors," the APA says. "Many think that nature and nurture both play complex roles; most people experience little or no sense of choice about their sexual orientation."

Carson suggested in a 2013 Fox News interview that legalizing gay marriage would pave the way for legal bestiality and pedophilia. He later apologized for the remark, but argued it "was taken completely out of context and completely misunderstood."

“As a Christian, I have a duty to love all people and that includes people who have other sexual orientations, and I certainly do, and never had any intention of offending anyone… If anyone was offended, I apologize to you," Carson said.

According to the Human Rights Campaign, other potential GOP candidates have weighed in on LGBT issues, including former Arkansas Gov. Mike Huckabee, who said he thinks being gay is a personal choice, and Sen. Ted Cruz (R-Texas), who said engaging in "homosexual conduct is a choice."

“The only thing that’s really been proven here is that when Ben Carson says what he really thinks, he reveals himself as utterly unfit for office," Sainz said. "Ben Carson is putting his own personal ambition ahead of medical science by suggesting that a person can change their sexual orientation. As a doctor, Carson surely knows that countless mental health and medical organizations have condemned the idea that you can change a person’s sexual orientation.”

Watch Carson's remarks above.

This post has been updated with information on other Republicans' views on LGBT issues and a statement from the Human Rights Campaign.